The peroxisome is a small organ present in the cells of animals and plants, and its matrix contains various enzymes such as catalases. The peroxisome proliferators are a substance inducing proliferation of the peroxisome. Various compounds such as fibrates, herbicides, and phthalic acid plasticizers are known to be able to induce proliferation of peroxisome.
Isseman, et al. have identified a nuclear receptor which is activated by the peroxisome proliferator and given a name of peroxisome proliferator activated receptor (PPAR).—Nature, 347, p 645–650, 1990.
As PPAR, three subtypes such as PPARα, PPARγ and PPARδ have been identified until now.—Proc. Natl. Acad. Sci. USA, 91, p 7335–7359, 1994.
The above-mentioned fibrates have a ligand effect on PPARα and are confirmed to show a strong serum TG (triglyceride) lowering effect in their clinical uses. Further, thiazolidine compounds (Troglitazone, Rosiglitazone, Pioglitazone) useful in the treatment of diabetes are also known as ligands of PPARγ.
As a pharmaceutical having PPARδ activating effect, there are known GW-2433 (Glaxo Wellcome), L-165041 (Merck), and YM-16638 (Yamanouchi Pharmaceutical) each having the following formula:
GW-2433 (Glaxo Wellcome)
L-165041 (Merck)
YM-16638 (Yamanouchi Pharmaceutical)

WO 92/10468 describes that GW-2433 is employable for prevention and treatment of atherosclerosis.
WO 97/28115 describes that L-165041 is employable for treatment of diabetes and suppression of obesity.
WO 99/04815 describes that YM-16638 shows effects for reducing serum cholesterol and reducing LDL cholesterol.
Recently, JBC, 272(6), p 3406–3410, 1997 and Cell, 99, p 335–345, 1999 describe proposal for application of PPAR δ ligand as an anti-cancer agent and an anti-inflammatory agent.
The above-mentioned GW-2433 and L-165041 are substituted phenoxyacetic acid derivatives and YM-16638 is a substituted thiaziazole-thioacetic acid derivative. Thus, they are apparently different in their structure from the substituted phenylacetic acid derivative of the invention having the below-mentioned formula (II).
As the substituted phenylacetic acid derivatives, wo 9958510 describes the following compound A, WO 9946232 describes the following compound B, and EP 908454 and WO 9815274 describe the following compound C:

Each of the above-mentioned compounds A, B and C has a structure in which the oxazole ring connects to the phenylacetic acid via an alkylene chain having an oxygen atom, while the compound of the invention having the below-mentioned formula (II) has no such ether bonding between the oxazole ring and the phenylacetic acid.